1. Field of the Invention
The invention relates in general to an atmospheric pressure plasma jet apparatus, and more particularly to a wide area atmospheric pressure plasma jet apparatus.
2. Description of the Related Art
Atmospheric pressure plasma refers to the plasma generated at an atmospheric pressure or near an atmospheric pressure. Compared with the conventional vacuum plasma technology, the atmospheric pressure plasma system is definitely advantaged in terms of cost. In terms of equipment cost, the expensive and heavy vacuum equipment is not required. In terms of manufacturing process, the work piece is not restricted by the vacuum cavity, and continuous type manufacturing process is applicable. The technical features effectively reduce manufacturing cost, and the system can be configured in small and portable equipment according to actual needs, hence making the area of application wider.
Atmospheric pressure plasma is generated by driving an electric field between two electrodes at normal atmospheric pressure, wherein plasma is generated when the gas between the electric field avalanches and becomes dissociated. There are different types of plasma source and design which can be classified as corona discharge, dielectric barrier discharge, plasma jet and plasma torch according to the form of plasma. Plasma jet is advantaged by having concentrated energy and fast processing speed. However, under the requirement of large-sized area, to process the surface treatment of the work piece by way of atmospheric pressure plasma and at the same time meet the requirements of low temperature and fast speed, normally multiple plasma-generating devices are used. As the cost of multiple plasma-generating devices is relatively high, many manufacturers withdraw from employing multiple plasma-generating devices due to cost benefit consideration.
Currently, the effect of large area plasma processing is normally achieved by dielectric barrier discharge technology. Despite dielectric barrier discharge technology is capable of processing a large area, there are many problems such as lower processing rate (due to weaker power) and discharge of equipment, therefore the system and the work piece are very close to each other, and the gap therebetween must be as small as a few millimeters. Besides, as the manufacturing equipment is easily over-heated, the manufacturing process of dielectric barrier discharge technology is not applicable to many polymer materials.
Furthermore, the plasma cleaning mechanism mainly uses the chemical reaction between the electrons or ions of plasma and the surface of the base material. However, is will cause to etch the surface and there are micro-particles left on the surface after cleaning process, and affect subsequent manufacturing process.